CN102035216B - Grid-connected control method and device for combining generator and matrix converter - Google Patents

Abstract

The invention discloses a grid-connected control method for combining a generator and a matrix converter, which comprises the following steps of: estimating a back electromotive force signal by utilizing the three-phase end voltage of the generator and the current of a winding, and then computing a phase-angle value through a phase-locked loop to be used as the phase angle of the three-phase input current reference signal of the matrix converter; computing the phase angle by utilizing the three-phase voltage of an electric network, and respectively computing the networking current and the quadrature-axis and direct-axis components of electric-network voltage to obtain the feedback values of actual networking active power and reactive power; using the output values of the deviation amounts of the set values and the feedback values through a PI (Proportion Integral) regulator as the direct-axis and quadrature-axis components of the expected output voltage of the matrix converter to obtain the three-phase voltage so as to regulate a duty-ratio signal; and obtaining the driving signal of a corresponding switching tube by adopting the instantaneous-value synthesis modulation strategy of the matrix converter. The matrix converter can effectively realize the function of a grid-connected inverter through the control method. The invention also discloses a grid-connected control device for combining the generator and the matrix converter.

Description

Grid-connected control method and the device of generator and matrix converter combination

Technical field

The invention belongs to power field, particularly generate electricity by way of merging two or more grid systems control method and the implement device thereof of the combination of a kind of generator and matrix converter.

Background technology

Along with socioeconomic development, electricity needs is growing, and day by day consuming of the non-renewable fossil energies such as oil, coal must impel people to seek new generation mode.Utilize the various available energy with disperseing to exist, comprise that the distributed generation system of regenerative resource (solar energy, wind energy, water energy etc.) is expected to become the trend of power system development.

In the utilization of wind energy, water energy, usually need generator that mechanical energy is converted to electric energy, because the unsteadiness of regenerative resource, it is constant that the rotating speed of generator can not keep usually, the frequency of its output electric energy also changes, therefore need converters as the interface between generator and the electrical network, the transformation of electrical energy that generator is exported is that the delivery of electrical energy that satisfies electrical network amplitude, phase place and harmonic wave content requirement uses to the user.

AC power converting apparatus can be divided into AC-DC-AC type and two kinds of forms of ac-ac type usually, and wherein, AC-DC-AC type power-converting device is widely applied because it has good control performance, but, there is dc energy storage electric capacity in it, and the volume of converting means is large, and is maintainable low.Matrix converter be a kind of can realize inputting mutually from m convert directly to the power-converting device that n exports mutually, can realize the multiple conversion such as AC-AC, AC-DC.Compare with traditional AC-DC-AC type power-converting device, matrix converter has that input power factor is high, input current waveform good, energy capable of bidirectional flowing, can realize four quadrant running, without intermediate dc energy storage link, the advantage such as circuit structure is compact, volume is little.The grid-connected system of generator and matrix converter combination has high power density, high reliability, can realize the high-quality electric energy output of low harmonic content, is one of preferred version of grid-connected system.Therefore, the inventor in order to realize effective combination of generator and matrix converter, proposes a kind of grid-connected control method namely based on above-mentioned thinking, and this case produces thus.

Summary of the invention

Technical problem to be solved by this invention is for the defective in the aforementioned background art and deficiency, and grid-connected control method and the device of a kind of generator and matrix converter combination is provided, and it can make matrix converter effectively realize the function of grid-connected converter.

The present invention is for solving the problems of the technologies described above, and the technical scheme that adopts is:

The grid-connected control method of a kind of generator and matrix converter combination comprises the steps:

(1) at the generating pusher side, detect three phase terminals voltage and the three-phase winding current of generator, estimate accordingly the back-emf signal of generator;

(2) the three-phase back-emf signal with aforementioned generator calculates its angle values φ by phase-locked loop, and with the phase angle of φ as matrix converter three-phase input current reference signal;

(3) in grid side, the three-phase voltage of detection of grid calculates the phase angle theta of line voltage by phase-locked loop;

(4) take line voltage phase angle q under the rotating coordinate system of benchmark, calculate respectively friendship axle and the direct axis component of networking electric current and line voltage i _d, i _q, U _dWith U _q, obtain actual networking active power through active power and reactive power calculating PWith reactive power QValue of feedback;

(5) with the active power set-point P ^*With aforementioned active power feedback value PThe output valve of departure behind pi regulator as the direct axis component of matrix converter desired output voltage v _d, the reactive power set-point Q ^*With aforementioned reactive power value of feedback QThe output valve of departure behind pi regulator as the quadrature axis component of matrix converter desired output voltage v _q, with aforementioned v _d, v _qTwo components are transformed under the rest frame take the line voltage phase angle theta as benchmark, obtain the three-phase voltage of matrix converter desired output v _a, v _bWith v _c, regulate the duty cycle signals of matrix converter with this;

(6) adopt the instantaneous value of matrix converter to synthesize modulation strategy, obtain the driving signal of corresponding switching tube.

In the above-mentioned steps (1), the formula of the back-emf signal of estimation generator is:

Wherein, u _u, u _v, u _wBe respectively the three phase terminals voltage of generator output, i _u, i _v, i _wBe respectively generator three-phase winding current, L _aBe generator phase winding inductance, R _aBe generator phase winding resistance.

In the above-mentioned steps (6), the content of the synthetic modulation strategy of instantaneous value is:

The input current reference signal of matrix converter is divided into 6 sectors, its division rule is: the positive-negative polarity of three-phase input current reference signal remains unchanged in the time a sector, with mutually be defined as different from all the other two-phases of three-phase input current reference signal Semi-polarity i _Base, being one of the variation of rising in all the other two-phases and being defined as mutually i _Inc, being one of the variation that descends and being defined as mutually i _Dec, corresponding three-phase input voltage is defined as respectively mutually with it U _Base, U _Inc, U _Dec

With desired output line voltage v _Ab, v _Bc, v _CaAlso be divided into 6 sectors, its division rule is: the maximum of three-phase desired output line voltage, and median, the order of minimum value remains unchanged, and is defined as respectively V _Max, V _Mid, V _Min

When i _BaseFor on the occasion of the time:

When i _BaseDuring for negative value:

。

The grid-connection control device of a kind of generator and matrix converter combination comprises main control unit, generator, input filter, matrix converter, output filter, isolating transformer, dynamo current detecting unit, terminal voltage detecting unit, network voltage detection unit, networking current detecting unit, driving isolation circuit, relay and the control switch that is incorporated into the power networks;

Wherein, generator and matrix converter three-phase input end directly link to each other; Input filter is parallel to the input of matrix converter;

The dynamo current detecting unit is measured the generator windings size of current, the terminal voltage detecting unit is measured the input voltage amplitude of matrix converter, the networking current detecting unit detects the networking size of current, the line voltage that the network voltage detection unit measures, aforementioned measurements all inputs to main control unit, this main control unit is through calculating in real time the control signal of matrix converter, and obtains driving signal through the driving isolation circuit;

The output of output filter series connection access matrix converter; The Y-connection winding of isolating transformer connects the output of output filter, and via this output filter connection matrix converter, the triangle of the other end connects winding and then connects electrical network via the control switch that is incorporated into the power networks; Relay is connected with the control switch that is incorporated into the power networks, and it drives signal and is exported by main control unit.

Above-mentioned input filter adopts three electric capacity that are Y-connection, and its three outputs are parallel to respectively the three-phase input end of matrix converter.

Above-mentioned output filter is three inductance, connects with the three-phase output end of matrix converter respectively.

After adopting such scheme, the present invention has realized the High Power Factor control of generator by the estimation to the generator back-emf, obtain the desired output voltage of matrix converter by the closed-loop control to be incorporated into the power networks active power and reactive power, classifying rationally is carried out in the input and output sector, realized effective control to matrix converter with the duty ratio computing formula of adopt deriving.

Description of drawings

Fig. 1 is the integrated stand composition of control device provided by the present invention;

Fig. 2 is the structured flowchart of the three-phase phase-locked loop that adopts among the present invention;

Fig. 3 is the division schematic diagram of matrix converter input side sector among the present invention;

Fig. 4 is the division schematic diagram of matrix converter outlet side sector among the present invention;

Fig. 5 is the distribution schematic diagram of the interior duty ratio of switch periods among the present invention.

Embodiment

Below with reference to drawings and the specific embodiments content of the present invention is elaborated.

The invention provides the grid-connected control method of a kind of generator and matrix converter combination, comprise the steps:

(1) at the generating pusher side, detect three phase terminals voltage and the three-phase winding current of generator, estimate accordingly the back-emf signal of generator, specifically can be calculated by following formula:

Wherein, u _u, u _v, u _wBe respectively the three phase terminals voltage of generator output, i _u, i _v, i _wBe respectively generator three-phase winding current, L _aBe generator phase winding inductance, R _aBe generator phase winding resistance.

(2) with the three-phase back-emf signal of aforementioned generator by phase-locked loop (can cooperate simultaneously Fig. 2), calculate its angle values φ, and with the phase angle of φ as matrix converter three-phase input current reference signal, see following formula, thereby realize the High Power Factor control of generator;

(3) in grid side, the three-phase voltage of detection of grid calculates the phase angle theta of line voltage by phase-locked loop shown in Figure 2, but this moment, its input three-phase voltage was line voltage u _a, u _b, u _c, and with the synchronizing signal of this angle as the coordinate transform of three-phase networking electric current;

(4) take line voltage phase angle q under the rotating coordinate system of benchmark, calculate respectively friendship axle and the direct axis component of networking electric current and line voltage i _d, i _q, U _dWith U _q, obtain actual networking active power through active power and reactive power calculating PWith reactive power QValue of feedback, specific formula for calculation is as follows:

(5) with the active power set-point P ^*With aforementioned active power feedback value PThe output valve of departure behind pi regulator as the direct axis component of matrix converter desired output voltage v _d, the reactive power set-point Q ^*With aforementioned reactive power value of feedback QThe output valve of departure behind pi regulator as the quadrature axis component of matrix converter desired output voltage v _q, with aforementioned v _d, v _qTwo components are transformed under the rest frame take the line voltage phase angle theta as benchmark, obtain the three-phase voltage of matrix converter desired output v _a, v _bWith v _c, regulate the duty cycle signals of matrix converter with this, realize the be incorporated into the power networks closed-loop control of active power and reactive power of electricity generation system;

(6) adopt the instantaneous value of matrix converter to synthesize modulation strategy, obtain the driving signal of corresponding switching tube;

The input current reference signal of matrix converter is divided into 6 sectors by shown in Figure 3, and its division rule is: the positive-negative polarity of three-phase input current reference signal remains unchanged in the time a sector.In control method provided by the present invention, with mutually be defined as different from all the other two-phases of three-phase input current reference signal Semi-polarity i _Base, being one of the variation of rising in all the other two-phases and being defined as mutually i _Inc, being one of the variation that descends and being defined as mutually i _Dec, corresponding three-phase input voltage is defined as respectively mutually with it U _Base, U _Inc, U _Dec

With desired output line voltage v _Ab, v _Bc, v _CaAlso be divided into 6 sectors, as shown in Figure 4, its division rule is: the maximum of three-phase desired output line voltage, and median, the order of minimum value remains unchanged, and is defined as respectively V _Max, V _Mid, V _Min

According to above definition, the instantaneous value of desired output line voltage can be synthesized by the instantaneous value of its input voltage, specifically can be expressed as following formula:

When i _BaseFor on the occasion of the time:

The physical significance of following formula is: V _MaxWith V _MinTwo output line voltages are synthetic by two input line voltages, are respectively U _BaseWith U _IncBetween line voltage U _Base-incWith U _BaseWith U _DecBetween line voltage U _Base-decBecause V _MinBe negative value, and work as i _BaseFor on the occasion of the time, U _Base-incWith U _Base-decBe on the occasion of, therefore actual synthetic output line voltage be- V _Min

When i _BaseDuring for negative value:

The physical significance of following formula with i _BaseFor on the occasion of the time similar because V _MaxBe on the occasion of, and work as i _BaseDuring for negative value, U _Base-incWith U _Base-decBe negative value, therefore actual synthetic output line voltage be- V _Max

For making the input current sineization, definition input current spread factor is a, is expressed from the next:

For making i _BaseFor the unification in duty ratio is calculated of positive two kinds of situations of negative value, right U _Base-incWith U _Base-decTake absolute value and calculate.The duty ratio of the switching tube that the matrix converter selection is opened can be expressed from the next:

Wherein, T ₁, T ₂With T ₃Expression is synthetic V _MaxThe duty ratio of line voltage, T ₄, T ₅With T ₆Expression is synthetic V _MinThe duty ratio of line voltage is in any switch periods T _sInterior switching mode is synthetic can be by shown in Figure 5.

In addition, as shown in Figure 1, the present invention also provides the grid-connection control device of a kind of generator and matrix converter combination, comprise main control unit, generator, input filter, matrix converter, output filter, isolating transformer, dynamo current detecting unit, terminal voltage detecting unit, network voltage detection unit, networking current detecting unit, driving isolation circuit, relay and the control switch that is incorporated into the power networks, wherein, generator directly links to each other with the three-phase input end of matrix converter; Input filter adopts three electric capacity that are Y-connection, and its three outputs are parallel to respectively the three-phase input end of matrix converter, and the close power tube wherein of trying one's best; The dynamo current detecting unit is used for measuring the generator windings size of current; The terminal voltage detecting unit is used for measuring the input voltage amplitude of matrix converter, and its wiring should be tried one's best near input filter.

Output filter is three inductance, seals in respectively the output of matrix converter; The input of isolating transformer connects the output of output filter, and via this output filter connection matrix converter, the other end then connects electrical network via the control switch that is incorporated into the power networks, and the input side of described isolating transformer is Y-connection, outlet side connection triangular in shape; Relay is used for controlling the control switch that is incorporated into the power networks, and it drives signal and is exported by main control unit.

The networking current detecting unit is for detection of the networking size of current; The network voltage detection unit is for the line voltage that measures, and its wiring is connected with the star input of isolating transformer.

The data that main control unit reception dynamo current detecting unit, terminal voltage detecting unit, network voltage detection unit, networking current detecting unit gather, and realization following functions: back-emf estimation and phase-locked loop thereof calculate, the input and output sector is judged, line voltage is phase-locked, the PI closed-loop control of active power and reactive power, coordinate transform, duty ratio is calculated, switch combination control.

The driving isolation circuit is connected between main control unit and the matrix converter, realizes light-coupled isolation between control signal and driving signal.

Above embodiment only for explanation technological thought of the present invention, can not limit protection scope of the present invention with this, every technological thought that proposes according to the present invention, and any change of doing on the technical scheme basis all falls within the protection range of the present invention.

Claims (2)

1. the grid-connected control method of a generator and matrix converter combination is characterized in that comprising the steps:

(1) at the generating pusher side, detect three phase terminals voltage and the three-phase winding current of generator, estimate accordingly the back-emf signal of generator;

(2) the three-phase back-emf signal with aforementioned generator calculates its angle values by phase-locked loop

And will

Phase angle as matrix converter three-phase input current reference signal;

(3) in grid side, the three-phase voltage of detection of grid calculates the line voltage phase angle theta by phase-locked loop;

(4) under the rotating coordinate system take the line voltage phase angle theta as benchmark, calculate respectively friendship axle and the direct axis component i of networking electric current and line voltage _d, i _q, U _dAnd U _q, calculate the value of feedback that obtains actual networking active-power P and reactive power Q through active power and reactive power;

(5) with active power set-point P ^*With the output valve of departure behind pi regulator of the aforementioned active-power P value of feedback direct axis component v as matrix converter desired output voltage _d, reactive power set-point Q ^*With the output valve of departure behind pi regulator of the aforementioned reactive power Q value of feedback quadrature axis component v as matrix converter desired output voltage _q, with aforementioned v _d, v _qTwo components are transformed under the rest frame take the line voltage phase angle theta as benchmark, obtain the three-phase voltage v of matrix converter desired output _a, v _bAnd v _c

(6) adopt the instantaneous value of matrix converter to synthesize modulation strategy, obtain the driving signal of corresponding switching tube; The content of the synthetic modulation strategy of described instantaneous value is:

The input current reference signal of matrix converter is divided into 6 sectors, its division rule is: the positive-negative polarity of three-phase input current reference signal remains unchanged in the time a sector, with three-phase input current reference signal Semi-polarity different from all the other two-phases one be defined as mutually i _Base, being one of the variation of rising in all the other two-phases and being defined as mutually i _Inc, being one of the variation that descends and being defined as mutually i _Dec, corresponding three-phase input voltage is defined as respectively U mutually with it _Base, U _Inc, U _Dec

With desired output line voltage v _Ab, v _Bc, v _CaAlso be divided into 6 sectors, its division rule is: the maximum of three-phase desired output line voltage, and median, the order of minimum value remains unchanged, and is defined as respectively V _Max, V _Mid, V _Min

Work as i _BaseFor on the occasion of the time:

V _max=T ₁U _base-inc+T ₂U _base-dec

-V _min=T ₄U _base-inc+T ₅U _base-dec

Work as i _BaseDuring for negative value:

-V _max=T ₁U _base-inc+T ₂U _base-dec

V _min=T ₄U _base-inc+T ₅U _base-dec；

Wherein, U _Base-incExpression U _BaseWith U _IncBetween line voltage, U _Base-decExpression U _BaseWith U _DecBetween line voltage;

Definition input current spread factor is α, is expressed from the next:

$\mathrm{\α}=\frac{i_{\mathrm{dec}}}{i_{\mathrm{inc}}}=\frac{T_2}{T_1}=\frac{T_5}{T_4}$

The duty ratio of the switching tube that the matrix converter selection is opened is expressed from the next:

$T_1=T_s\frac{V_{\max }}{\left|U_{\mathrm{base}-\mathrm{inc}}\right|+\mathrm{\α}\left|U_{\mathrm{base}-\mathrm{dec}}\right|}$

$T_2=T_s\frac{\mathrm{\α}{V}_{\max }}{\left|U_{\mathrm{base}-\mathrm{inc}}\right|+\mathrm{\α}\left|U_{\mathrm{base}-\mathrm{dec}}\right|}$

T ₃=T _s-T ₁-T ₂

$T_4=T_s\frac{V_{\min }}{\left|U_{\mathrm{base}-\mathrm{inc}}\right|+\mathrm{\α}\left|U_{\mathrm{base}-\mathrm{dec}}\right|}$

$T_5=T_s\frac{\mathrm{\α}{V}_{\min }}{\left|U_{\mathrm{base}-\mathrm{inc}}\right|+\mathrm{\α}\left|U_{\mathrm{base}-\mathrm{dec}}\right|}$

T ₆=T _s-T ₄-T ₅

Wherein, T ₁, T ₂And T ₃The synthetic V of expression _MaxThe duty ratio of line voltage, T ₄, T ₅And T ₆The synthetic V of expression _MinThe duty ratio of line voltage, T _sThe expression switch periods.

2. the grid-connected control method of generator as claimed in claim 1 and matrix converter combination, it is characterized in that: in the described step (1), the formula of back-emf signal of estimation generator is:

$e_u=u_u+L_a\frac{{\mathrm{di}}_u}{\mathrm{dt}}+R_a{i}_u$

$e_v=u_v+L_a\frac{{\mathrm{di}}_v}{\mathrm{dt}}+R_a{i}_v$

$e_w=u_w+L_a\frac{{\mathrm{di}}_w}{\mathrm{dt}}+R_a{i}_w$

Wherein, u _u, u _v, u _wBe respectively the three phase terminals voltage of generator output, i _u, i _v, i _wBe respectively generator three-phase winding current, L _aBe generator phase winding inductance, R _aBe generator phase winding resistance.

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